1. Field
The present invention relates to a fiber distribution terminal having an internal spool for storing and protecting fiber cable.
2. Background
A Fiber Distribution Terminal (FDT) is used to interconnect multiple fibers, typically originating from a common point, and distributed to multiple different locations with output fiber cables. A FDT typically comprises an enclosure wherein connections are made between a larger multi-fiber bundle input cable and individual output fiber cables. The typical application configuration for the use of an FDT is in buildings such as multi-unit residences or commercial/office buildings. There could be a single FDT per building or perhaps one or more per floor or any combination in between depending on the fiber connection needs and capacity of the building.
One recurring issue faced when dealing with the installation of FDTs is how much input fiber is required to connect the FDT to some common point, which is often outdoors where the connections to the larger fiber networks (e.g., city wide fiber network) are made. The common point could also be within the same building, perhaps on another floor or in the basement of the building. No matter the location of the common point, the issue remains that it is often necessary to physically locate the FDT before the approximate required length of fiber cable is known. Issues involved with not knowing the required length of fiber cable could present themselves in at least two ways. First, it might be necessary to approximate and prepare a length of fiber cable before installation of the FDT occurs. If the approximation is too short then the connection to the FDT cannot be made without further fiber cable splices or another length of fiber cable will have to be obtained. Conversely, if the approximation is too long, then the excess slack of fiber cable will have to be stored somewhere along the length of fiber cable. This creates the possibility of introducing unwanted bends and thus unwanted bend loss into the fiber cable path. Second, it might be necessary to relocate the FDT so that the chosen or available fiber cable length is approximately correct, which could mean placing the FDT in an undesirable location. These problems arise because there is presently no safe way to store excess fiber cable after installation nor feed fiber cable from an installed FDT. Another problem is that there is no convenient way to store the input fiber cable prior to installation of the FDT.
It would be convenient to affix the box to its permanent location and to make the input fiber cable connections before having to connect the input fiber cable to the common point. Presently this is not possible. There are FDTs available that include an external spool of fiber cable but they do not allow the FDT enclosure to be affixed to its permanent location because the enclosure must rotate with the external spool of fiber cable. This also prevents the installer from making the input fiber connections to the adapter pack prior to connection of the input fiber cable.
Available FDTs have only one output direction for the input and output fiber cables that are entering and exiting the FDT enclosure. This ensures that the routing of the cables internal to the enclosure is always oriented in the same direction. But this often makes the external installation difficult and the routing of cables external to the FDT enclosure cumbersome. This can occur in situations where the external fiber routing needs to go to a higher floor and the FDT only has fiber cable outputs to the bottom of the enclosure (relative to the mounting orientation), meaning that the fiber cables must make a 180 degree turn after they leave the enclosure. This often results, especially with less experienced installers, in damage to the fiber cable, usually due to inadvertent bend loss.
It is also important to protect the fiber cables when they are internal to the FDT enclosure. Typical enclosures contain connection blocks where the fibers of the larger input cable are individually matched to single output cables. Both the input and output cables are separately routed through the enclosure, with the installer having the responsibility of routing the fiber cables in such a way so as to avoid bends in the cable and thus bend loss. Installers, who may or may not be conscious of this responsibility, might not always appreciate the impact of their craftsmanship. Routing secured by cable ties or other more industrial type retaining clips could easily create inadvertent bends in the fiber cables, thus causing undesired loss of signal strength in the fiber cables.
Therefore, it is desirable to have a FDT that conveniently stores fiber cable prior to installation and houses excess fiber cable after the input cable connection has been made. It is also desirable for the FDT to house the input fiber cable to output fiber cable connections and safely route the cables internal to the FDT enclosure to avoid bend loss while allowing the input and output fiber cables to enter/exit through either of two sides to the enclosure.